#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#define PI 3.1415926

int main() {
    double r = 0.0;
    double v = 0.0;
    scanf("%lf", &r);
    v = 4 / 3.0 * r * r * r * PI;
    printf("%.3lf\n", v);
    return 0;
}